“Rocks form an elementary building block of my work, both regarding design and cultivation.”

The natural scientist, horticulturist and specialist author, Sven Nürnberger, has taken some time to meet with GRÜNES BLUT in the Palmengarten Frankfurt before one of his talks.  We talk about his work in the Palmengarten rockery and about his eagerness to share his expert knowledge.

After our earlier telephone conversation, I realised we would ultimately need two interviews! Apart from the knowledge he has gained – and implemented – through his trips to the natural habitats of botanical rarities, he has also done some fantastic work in the Frankfurt Palmengarten. On the one hand, his work here is too significant to ascribe it merely to what he has learnt from his travels.  And on the other hand, an interview would seem incomplete if we ignored the “why” of his trips. Therefore, I was delighted when Sven enthusiastically agreed to a second interview.

Read: 15 min

Interview: Sven Nürnberger, Anke Schmitz ∗ Texteditor: Anke Schmitz ∗ Photos: Anke Schmitz ∗ Translation: Gisela Lindeque

Sven, I’ll get straight to the point. To what extent does your work here relate to your travels?

SN: On the one hand, of course, I need to develop and broaden my knowledge of specific plants. In other words, I need to know the conditions the plants need and their demands on a site to appropriately apply this to our climate in Frankfurt. On the other hand, I feel it’s important to understand the composition of the vegetation or the plant community.  In that respect, it’s always advantageous to have seen these plants in their natural settings. Of course, it’s not essential. You can also get a good idea from books, reports and presentations. But in principle, at least for myself, it supplements or fills some gaps in my knowledge.

The gardening profession is a never-ending learning environment.

GB: I assume it also helps when you practically experience these things and observe or sense nature during your trips.

SN: Exactly! I believe this is also very crucial. When you travel, you tend to internalise things much more. But this probably depends on your personality. Traveling gives me a sense of the overall impact of a location and the potential interpretations in a garden.

GB: What, generally, has drawn you to the gardening profession? Is it possible to summarise this in three or four concise sentences?

SN: The gardening profession is a never-ending learning environment. You continuously get fresh inspiration and you can work with such diverse plant groups. In my case, I focus on outdoor plants, mainly perennials. I also find working with living organisms fantastic because I experience a special connection. But then I also like to consider so-called inanimate nature. Rocks form the basis of soil, which in turn is animated by organisms. Rocks form an elementary building block of my work, both regarding design and cultivation. I’m encouraged as well by the networking and exchange among interested international gardeners. I love sharing in their enjoyment of plants.  These people make no distinction between their professional and private interest in plants and they’re continually feeding their curiosity and passion.

The south-eastern slope of the rock garden with Libertia, Trachystemon and Dysosma.

GB: What do you consider unique about your workplace, the Palmengarten?

SN: I experience the Palmengarten as a melting pot of different disciplines, both in its historical background as well as in the current assortment – a tension between different styles and scientific aspects of the collections. It’s very gratifying to work with large-scale areas, to develop concepts and to maintain and optimise the results. The Palmengarten embodies a botanical garden oriented toward plant sociology (collections, plant geography) and, because of Heinrich Siesmayer, boasts ornamental and show gardens. I love the holistic approach and the opportunities for professional development as well as the public relations and educational aspects of my job in the Palmengarten.

However, the gravel heaps you see in many front gardens today represent an extreme shift away from nature and gardening.

GB: The rock garden with its integrated grotto forms a large part of ​​your field of responsibility here. The term rock garden is currently used for quite a variety of small garden designs.  This can be very confusing. What exactly is an authentic rock garden and how is it distinguished from a crevice garden or an alpinum (alpine garden), which you both have here?

SN: In principle, front gardens are an excellent medium for installing a rock garden, since a small area is ideal for a design containing small plants and a rock island. However, the gravel heaps you see in many front gardens today represent an extreme shift away from nature and gardening. If you want to create a minimalist look, you can design quite an attractive and low-maintenance scenery like, for example, an Alpine scree slope or a moraine field. The plant combinations on these fleece-lined heaps are, however, rarely suited to the habitat and often consist of questionable combinations.  But to get back to your question: an alpinum represents the vegetation above the forest edge as well as open boreal areas. For example, rock, scree, lawn and creek plant communities, as well as marsh and Krummholz vegetation from temperate climates and Mediterranean high mountain regions. A rock garden can also portray or integrate other climate areas that are known for being rocky. For example, Felsheide aspects of Mediterranean flora, steppe elements, as well as miniature plants, annuals and hybrids. You, therefore, have more leeway than with an alpinum. And a crevice garden is, in fact, an aspect of a rock garden or an alpinum. It’s a simulation of an eroding, crumbling rock face in which plants find a vertical habitat.  In other words, a rock garden can basically incorporate a crevice garden and an alpinum. But a crevice garden or a rock garden is not necessarily also an alpinum. You can also find crevices in thermophilic Mediterranean regions, in the Rhine Valley and in tropical Brazil. In the tropical parts of America, rock walls are populated by, for example, bromeliads, plumeria and cacti. The botanical garden in Osnabrück has shown that is also possible to simulate a tropical rock wall. Their tropical greenhouse is attached to a quarry wall.

Libertia cf. chilensis

GB: Is this what draws you to a rock garden? Exploring the landscaping possibilities?

SN: Yes, indeed. Of course, I also have a basic interest in some specific plant groups. During the 1980s Ursula McHardy established a southern hemisphere theme for the rock garden in the Palmengarten. During the redesign (1985-1987) she divided the rock garden into different thematic areas, each containing different rock types.  Cultivars and geographic blending were included in the plans. Stylistically, she explicitly referred to the historic and contemporary requirements of the Palmengarten. In her garden in Crombie near Edinburgh, however, she focused on simulating southern hemisphere vegetation images. Her design and ecological implementation in this garden bore evidence of the long years she spent observing the natural habitats.  She left the Palmengarten in the mid-90’s. In 2011, I inherited her rock garden and began to re-work the areas, which had over the preceding years fallen into a kind of Sleeping-Beauty state. Currently, I’m busy expanding the collection of southern hemisphere plants and implementing a geographic focus. But I am also connecting the rock garden with its habitats – both ecologically and by creating more homogeneous as well as more complex geographic links. This is just as much an overhaul as a conceptual restructure, which is ultimately based on consistently extending and integrating Ursula McHardy’s pioneering work. I can now work with the distinctive aesthetic, integrative medium that she developed, a medium that demands respect for these habitats.  Such an inspiration! It gives me the practical scaffolding that can be individually adapted according to any desired scientific orientation. Because of our favourable climatic position – we are in hardiness zone 8a – our conditions are good for exotic plant groups, both southern hemisphere species and Asian monsoon plants. These days it’s very important to respond to noticeable change in climate by selecting suitable plants. Much of what was still possible in the past is now limited by periods of intense heat. These days plant groups like Dierama, Cortaderia and Watsonia, are seeding themselves in the Palmengarten.

View of the northern rock garden with Tussoc community and Gunnera tinctoria.

GB: Your winter protection in the rock garden is quite elaborate – at least at the level you’re operating here in the Palmengarten …

SN: I would almost say we need more winter protection in Frankfurt than in gardens with regular high snowfall and cooler summer temperatures. In some Alpine gardens at an altitude of 2000 m, such as in Chile, Argentina and New Zealand, certain plant groups can grow with fewer problems. But big temperature drops during the vegetation period, late frosts, minimum temperatures and short growth periods can create limitations for hardy plant groups, whereas in the Palmengarten we can experiment with these groups of plants. Here we usually have mild winter conditions, but we do experience black frost and winter dampness.  So, fleece protection or a leaf chute is definitely a sensible defence against black frost. Of course, the challenge in selecting the assortment is to balance out the whole story, so that we don’t spend the entire winter only on winter-protection. We try to find a balance between plantations needing extensive and intensive care. Testing for maximum hardiness also plays an important part – provided we have enough plant material.

GB: Do you propagate your own plants for the alpinum or do you often make use of external suppliers?  In the first part of our interview, when we spoke about the plants in the alpinum, you mentioned England as a place of procurement.

SN: We propagate a significant portion of the plants ourselves from seeds, or they reproduce vegetatively. We also believe it’s important to exchange plant material with other botanical gardens and institutes. But we do sometimes buy, especially when we need cultivars for our exhibition facilities.

I think it’s imperative to pass on the encouragement and inspiration you have received.

GB: You already spoke about Ursula McHardy.  You used to work with her and you were also friends.  What influence did she have on you?

SN: Ursula was a very open person, she could speak passionately about themes that excited her. It was very contagious.  She loved teachable people who wanted exciting new input things. She used to warmly welcome especially the younger generation and encouraged those who were hungry for more knowledge. Her lectures fascinated me. They were alive with content, always a bit different and she was brilliant at explaining ecological, geological and climatic subjects. It was merely part of who she was. During my apprenticeship, I worked in the rock garden for 3 months, and that’s when we got to know each other. Over the years, a remarkable friendship developed based on our shared interest in plants. Her analytical research spirit especially fascinated me. As a biologist, she was a brilliant connector of theory and horticultural practice, a collector, a cultivator and a designer all in one.  

GB: How did Ursula McHardy influence you in your profession?

SN: She inspired and encouraged me to become familiar with the southern hemisphere. I learnt from her to focus on the natural habitats of plants in order to understand their requirements. Also how to do the necessary relevant research while preparing for a botanical excursion.  She didn’t feel like a mentor, because she authentically imparted her knowledge and knew and understood herself well. A typical phrase of hers was: “It was you! You wanted to know!” I will always treasure this experience of having an open door whenever I wanted to learn and experiment. During my horticultural career, I have encountered many people with the same attitude. I think it’s imperative to pass on the encouragement and inspiration you have received.

For those who prefer the horizontal: Androsace lactea.

GB: That’s a wonderfully encouraging approach: It was you. You wanted to know!

SN: Yes. It’s very important to develop your self-esteem. Just make your knowledge available, be open and don’t withhold your wisdom.

GB: Aside from your shared interest, what else did you have in common?

SN: Ursula had such a childlike curiosity. It was as if it magically drove her forward. I also sense this in myself. Then whenever we would interact, with our similar ideas, our connection just grew. In my early gardening years, my visits with a friend to McHardy’s garden became a significant orientation. I used to get plant material to experiment with and so started discovering my favourite plants.  At some point, I also became more independent and could even acquire some knowledge on my own. And one day I had reached the point where I could also professionally return something. We started genuinely exchanging knowledge, and this was a beautiful development.

I was dealing with so much material and I really wanted to share it.

GB: How important is writing when you consider knowledge sharing and acquisition?

SN: During my childhood and adolescence I had a grandfatherly friend who introduced me to writing. During a school trip – when I was still fascinated by fossils and minerals – I had an incredible encounter with an agate and fossil collector who used to collect in the Kreuznach region. He was a bit of a muse, but at the same time also like a scientist. A chemist by nature, he inspired me so much that I gradually became hooked.  He loved using spoonerisms and would become very emotional about Goethe and a few other poets. He imparted this attitude to me like a grandfather, and soon I began writing my own poems and phrases. When I had been part of the Staudenfreunden for some years, someone suggested examining and writing articles for the Staudengarten magazine about a few plant groups or even about personal garden projects. I wrote three articles for the Staudenfreunde and then thought I would also try this for the Gartenpraxis, a magazine I liked. So in 2008 I impulsively phoned them after my Falklands trip and they were immediately interested.

GB: … and how! When I paged through the 2009 and 2010 editions, I found some of your plant photos in almost all of them.

SN: Yes. Somehow that’s what happened. I was dealing with so much material and I really wanted to share it.  Actually, it had been a deep desire, since the beginning of 2002 and I just had to wait, as I had to with my Patagonia trip.

Metallic shiny: Delosperma ‘Fire Spinner’.

GB: Do you find that working on your articles adds some kind of order to your knowledge, or are you already totally clear about it all and then you just write it down again for a broader readership?

SN: An article always involves a lot of long-term research as well as some current research, so I always learn a lot when writing one.  Basically, you have to summarise what you’ve been intensively grappling with or what you are specifically interested in and then you also learn many new things while writing. For example, the current taxonomy of a species etc.

GB:So, is it almost like completing your own knowledge?

SN:Exactly. Those are the two sides. Both the pleasure in highlighting some issues and passing on knowledge, as well as reflecting on it all and making it part of yourself.

I like to impart my own enthusiasm and to inspire others to try out these things on their own.

GB:What do your lectures, such as the one of today about your Patagonia trip, mean to you?

SN:In the case of today’s talk, I’m going to paint a picture of or illustrate my trip, and I want to share my enthusiasm for travel. But apart from this, I have a lecture cycle and give many talks on various topics throughout the year. And I also provide guided tours. I like to impart my own enthusiasm and to inspire others to try out these things on their own. In fact, it’s the same in my writing. I want to share my personal experience of several years and look at it all from a current perspective. Usually, a presentation topic lasts 2-3 years, and then it evolves and becomes part of a new course of talks. I might come up with something entirely new, or perhaps a recent or upcoming trip will suddenly move to the foreground.

Sven at the small, yet beautiful, crevice garden (photo: Kristina Bakhtiari-Kish)

GB: We’re on the home stretch, Sven. What’s your best practical gardening tip? One we won’t easily find in a book.

SN: I think it’s very, very important to observe. For example, what promotes plant growth? Is it the use of fertilisers or the influence of temperature change? But you also need to observe the natural habitat.  Then you can form an idea on how to let a cultivated plant thrive.

GB:What’s your favourite garden tool?

SN:My favourite garden tool? I would say my planter. With it, I can both plant and weed. Apart from this I also prefer a light spade with a narrow blade.  Then it’s easier to do filigree work, which is essential to me. But in principle, it’s my eyes. Because I always value observation and I like to look at the plants from different viewpoints or compass directions – up close and from far away – to form one big picture.

GB: Sven, this been such a stimulating conversation. Thank you for your time and see you again soon!

This post is also available in: Deutsch (German)